In many engineering applications components are fabricated using a range of processing techniques. The techniques used are dependent upon the material from which the components are constructed and their intended application. For example, engineering components fabricated from metals and alloys are often processed using techniques such as extrusion, forging, drawing, bending, rolling and casting. Whilst these processes are often essential to produce a resultant component with the desired geometry, it is often difficult to produce components with dimensional geometries having sufficient accuracy to meet the engineering requirements.
This is because each of these processes may inherently cause dimensional deviations from those nominally required. Such distortions occur particularly in complex manufacturing processes where a number of individual processes are used serially in the fabrication of components.
Some minor distortions can be accommodated by engineering tolerances although in many cases the high tolerances required make further processing of the components essential in order to correct these distortions.
As an example, in the automotive industry high performance vehicles are often fabricated using a number of lightweight and high strength components using materials such as aluminium alloys. These components range from minor parts, to major members of vehicle bodies. In many cases these components are formed using extrusion techniques. Typical tolerances required in such applications are dimensional accuracies within 0.2 millimeters. These usually cannot be achieved using conventional forming processes such as extrusion.
At present the geometrical variations of formed components are provided with maximum dimensional accuracy by using well trimmed tooling and close control of the process parameters. If, however, this is insufficient to keep the dimensions within acceptable limits, some form of correction processing must be applied to the components in order to correct their geometry. Conventional methods for correcting such geometries are based on mechanical techniques where the components are mechanically deformed, cut or milled to produce the necessary corrections.
There are a number of major problems with the use of these correction processes. For example, the apparatus used to perform them is often extremely expensive and only has limited application for particular purposes. This is particularly costly where the number of components produced during a production run is small, as might be the case in the production of components for a high performance sports car. As the associated correction apparatus will usually be specifically designed for correcting a particular component, this adds great cost to the production of the component as a whole. Furthermore it may be inconvenient or even impossible to correct the geometry in certain regions of the component as access to the region in question may be very limited.
There is therefore an object of the present invention to provide a more versatile method of correcting such distortions in component workpieces.
In WO99/44764, a system is described which includes a database of data relating to the forming of plates, from which further data are inferred in the determination of appropriate heat treatments for plate forming.